package cn.tianyigps.tianyigpsapiv2.utils;

import com.spatial4j.core.context.SpatialContext;
import com.spatial4j.core.distance.DistanceUtils;

/**
 * Created with IntelliJ IDEA
 * Created By yangxl
 * Date: 2018/5/30
 * Time: 13:47
 * Description:计算两个Gps点的直线距离
 */
public class LocationUtils {
    public static double EARTH_RADIUS = 6378.137;
    public static double TO_METER = 1000;

    private static double rad(double d) {
        return d * Math.PI / 180.0;
    }

    /**
     * 通过经纬度获取距离(单位：米)
     * @param lat1
     * @param lng1
     * @param lat2
     * @param lng2
     * @return
     */
    public static double getDistance(double lat1, double lng1, double lat2,
                                     double lng2) {
        double radLat1 = rad(lat1);
        double radLat2 = rad(lat2);
        double a = radLat1 - radLat2;
        double b = rad(lng1) - rad(lng2);
        double s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a / 2), 2)
                + Math.cos(radLat1) * Math.cos(radLat2)
                * Math.pow(Math.sin(b / 2), 2)));
        s = s * EARTH_RADIUS;
        s = Math.round(s * 10000d) / 10000d;
        s = s*1000;
        return s;
    }
    /**
     * 获取两点之间的距离(单位：KM)
     * @return
     * @author cui.guibin
     */
    public static double calcDistance(double lng1 , double lat1, double lng2, double lat2) {
        // 计算两定位之间距离
        SpatialContext geo = SpatialContext.GEO;
        return geo.calcDistance(geo.makePoint(lng1,lat1),geo.makePoint(lng2, lat2)) * DistanceUtils.DEG_TO_KM;
    }
}